Heat exchanger having curved fluid passages for a gas turbine engine

ABSTRACT

A heat exchanger for a gas turbine engine includes a heat exchanger body having a first surface and a second surface oriented at least partially at an oblique angle relative to the first surface. The heat exchanger body defines a plenum extending between the first and second surfaces. Furthermore, the heat exchanger body defines a fluid passage extending through the second surface such that the fluid passage is in fluid communication with the plenum. The fluid passage, in turn, includes first and second portions. The first portion intersects the plenum at an intersection and defines a line of projection extending normal to the second surface. The second portion defines a line of projection extending normal to the first surface. The fluid passage further includes a curved portion extending from the first portion to the second portion.

FIELD

The present subject matter relates to gas turbine engines and, moreparticularly, to heat exchanger having curved fluid passages for a gasturbine engine.

BACKGROUND

A turbofan engine generally includes a fan, a compressor section, acombustion section, and a turbine section. More specifically, the fangenerates a flow of pressurized air. A portion of this air flow is usedas propulsive thrust for propelling an aircraft, while the remaining airis supplied to the compressor section. The compressor section, in turn,progressively increases the pressure of received air and supplies thiscompressed air to the combustion section. The compressed air and a fuelmix within the combustion section and burn within a combustion chamberto generate high-pressure and high-temperature combustion gases. Thecombustion gases flow through the turbine section before exiting theengine. In this respect, the turbine section converts energy from thecombustion gases into rotational energy. This rotational energy, inturn, is used to drive the compressor section and/or the fan via variousshaft and/or gearboxes.

Typically, a turbofan engine includes various heat exchangers to heat orcool the fluids that support the operation of the engine. For example,the engine may include one or more heat exchangers that cool the oilcirculated through the gearbox(es) of the engine. While conventionalheat exchangers generally provide sufficient heating/cooling to thefluids of the engine, such heat exchangers increase the overall weightof the engine.

Accordingly, an improved heat exchanger for a gas turbine engine wouldbe welcomed in the technology. In particular, a heat exchanger for a gasturbine engine having a reduced weight would be welcomed in thetechnology.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one aspect, the present subject matter is directed to a heatexchanger for a gas turbine engine. The heat exchanger includes a heatexchanger body having a first surface and a second surface oriented atleast partially at an oblique angle relative to the first surface. Theheat exchanger body defines a plenum extending between the first andsecond surfaces. Furthermore, the heat exchanger body defines a fluidpassage extending through the second surface such that the fluid passageis in fluid communication with the plenum. The fluid passage, in turn,includes first and second portions. The first portion intersects theplenum at an intersection and defines a line of projection extendingnormal to the second surface. The second portion defines a line ofprojection extending normal to the first surface. The fluid passagefurther includes a curved portion extending from the first portion tothe second portion.

In another aspect, the present subject matter is directed to a gasturbine engine. The gas turbine engine includes a compressor, acombustor, a turbine, and a heat exchanger in operative association withat least one of the compressor, the combustor, or the turbine. The heatexchanger, in turn, includes a heat exchanger body having a firstsurface and a second surface oriented at least partially at an obliqueangle relative to the first surface. The heat exchanger body defines aplenum extending between the first and second surfaces. Furthermore, theheat exchanger body defines a fluid passage extending through the secondsurface such that the fluid passage is in fluid communication with theplenum. The fluid passage, in turn, includes first and second portions.The first portion intersects the plenum at an intersection and defines aline of projection extending normal to the second surface. The secondportion defines a line of projection extending normal to the firstsurface. The fluid passage further includes a curved portion extendingfrom the first portion to the second portion.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 is a schematic cross-sectional view of one embodiment of a gasturbine engine;

FIG. 2 is a schematic view of one embodiment of a heat exchangersuitable for use with a gas turbine engine;

FIG. 3 is a partial cross-sectional view of one embodiment of a heatexchanger suitable for use with a gas turbine engine, particularlyillustrating various portions of a plurality of fluid passages definedby a body of the heat exchanger;

FIG. 4 is a partial cross-sectional view of one embodiment of a heatexchanger suitable for use with a gas turbine engine, particularlyillustrating an intersection between a fluid passage defined by a heatexchanger body and a plenum defined by the body;

FIG. 5 is another partial cross-sectional view of one embodiment of aheat exchanger suitable for use with a gas turbine engine, particularlyillustrating a plenum defined by a heat exchanger body; and

FIG. 6 is a further partial cross-sectional view of one embodiment of aheat exchanger suitable for use with a gas turbine engine, particularlyillustrating the relative positioning of first and second pluralities ofthe fluid passages defined by a heat exchanger body.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

As used herein, the terms “first”, “second”, and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.

Furthermore, the terms “upstream” and “downstream” refer to the relativedirection with respect to fluid flow in a fluid pathway. For example,“upstream” refers to the direction from which the fluid flows, and“downstream” refers to the direction to which the fluid flows.

Additionally, the terms “low,” “high,” or their respective comparativedegrees (e.g., lower, higher, where applicable) each refer to relativespeeds within an engine, unless otherwise specified. For example, a“low-pressure turbine” operates at a pressure generally lower than a“high-pressure turbine.” Alternatively, unless otherwise specified, theaforementioned terms may be understood in their superlative degree. Forexample, a “low-pressure turbine” may refer to the lowest maximumpressure turbine within a turbine section, and a “high-pressure turbine”may refer to the highest maximum pressure turbine within the turbinesection.

In general, the present subject matter is directed to a heat exchangersuitable for use with a gas turbine engine. In several embodiments, theheat exchanger includes a heat exchanger body defining a plenum therein.The plenum, in turn, extends between first and second surfaces of theheat exchanger body, with the second surface oriented at least partiallyat an oblique angle relative to the first surface. Furthermore, the heatexchanger body further defines a plurality of fluid passages extendingthrough the second surface such that the fluid passages are fluidcommunication with the plenum. Each fluid passage, in turn, includesfirst and second portions. Specifically, the first portion of each fluidpassage intersects the plenum at an intersection and defines a line ofprojection (e.g., a centerline) extending normal to the second surfaceof the heat exchanger body. Moreover, the second portion of each fluidpassage define a line of projection (e.g., a centerline) extendingnormal to the first surface. Additionally, each fluid passage furtherincludes a curved portion extending from the corresponding first portionto the corresponding second portion.

Positioning the first portion of each fluid passage such that its lineof projection extends normal to the second surface (i.e., the surfacethrough which the passages extend to intersect the plenum) of the heatexchanger reduces the weight of the heater exchanger. More specifically,such a configuration reduces the stress concentrations present at theintersections of the fluid passages and the plenum during operation ofthe heat exchanger. This, in turn, allows the heat exchanger to beformed from lighter materials than conventional heat exchangers (e.g.,aluminum instead of steel), while still maintaining the same sizeenvelope and operating under the same fluid pressures.

Referring now to the drawings, FIG. 1 is a schematic cross-sectionalview of one embodiment of a gas turbine engine 10. In the illustratedembodiment, the engine 10 is configured as a high-bypass turbofanengine. However, in alternative embodiments, the engine 10 may beconfigured as a propfan engine, a turbojet engine, a turboprop engine, aturboshaft gas turbine engine, or any other suitable type of gas turbineengine. Furthermore, as shown in FIG. 1, the engine 10 defines alongitudinal direction L, a radial direction R, and a circumferentialdirection C. In general, the longitudinal direction L extends parallelto an axial centerline 12 of the engine 10, the radial direction Rextends orthogonally outward from the axial centerline 12, and thecircumferential direction C extends generally concentrically around theaxial centerline 12.

In general, the engine 10 includes a fan 14, a low-pressure (LP) spool16, and a high pressure (HP) spool 18 at least partially encased by anannular nacelle 20. More specifically, the fan 14 may include a fanrotor 22 and a plurality of fan blades 24 (one is shown) coupled to thefan rotor 22. In this respect, the fan blades 24 are spaced apart fromeach other along the circumferential direction C and extend outward fromthe fan rotor 22 along the radial direction R. Moreover, the LP and HPspools 16, 18 are positioned downstream from the fan 14 along the axialcenterline 12 (i.e., in the longitudinal direction L). As shown, the LPspool 16 is rotatably coupled to the fan rotor 22, thereby permittingthe LP spool 16 to rotate the fan 14. Additionally, a plurality ofoutlet guide vanes or struts 26 spaced apart from each other in thecircumferential direction C extend between an outer casing 28surrounding the LP and HP spools 16, 18 and the nacelle 20 along theradial direction R. As such, the struts 26 support the nacelle 20relative to the outer casing 28 such that the outer casing 28 and thenacelle 20 define a bypass airflow passage 30 positioned therebetween.

The outer casing 28 generally surrounds or encases, in serial floworder, a compressor section 32, a combustion section 34, a turbinesection 36, and an exhaust section 38. For example, in some embodiments,the compressor section 32 may include a low-pressure (LP) compressor 40of the LP spool 16 and a high-pressure (HP) compressor 42 of the HPspool 18 positioned downstream from the LP compressor 40 along the axialcenterline 12. Each compressor 40, 42 may, in turn, include one or morerows of stator vanes 44 interdigitated with one or more rows ofcompressor rotor blades 46. Moreover, in some embodiments, the turbinesection 36 includes a high-pressure (HP) turbine 48 of the HP spool 18and a low-pressure (LP) turbine 50 of the LP spool 16 positioneddownstream from the HP turbine 48 along the axial centerline 12. Eachturbine 48, 50 may, in turn, include one or more rows of stator vanes 52interdigitated with one or more rows of turbine rotor blades 54.

Additionally, the LP spool 16 includes the low-pressure (LP) shaft 56and the HP spool 18 includes a high pressure (HP) shaft 58 positionedconcentrically around the LP shaft 56. In such embodiments, the HP shaft56 rotatably couples the rotor blades 54 of the HP turbine 48 and therotor blades 46 of the HP compressor 42 such that rotation of the HPturbine rotor blades 54 rotatably drives HP compressor rotor blades 46.As shown, the LP shaft 56 is directly coupled to the rotor blades 54 ofthe LP turbine 50 and the rotor blades 46 of the LP compressor 40.Furthermore, the LP shaft 56 is coupled to the fan 14 via a gearbox 60.In this respect, the rotation of the LP turbine rotor blades 54rotatably drives the LP compressor rotor blades 46 and the fan blades24.

In several embodiments, the engine 10 may generate thrust to propel anaircraft. More specifically, during operation, air (indicated by arrow62) enters an inlet portion 64 of the engine 10. The fan 14 supplies afirst portion (indicated by arrow 66) of the air 62 to the bypassairflow passage 30 and a second portion (indicated by arrow 68) of theair 62 to the compressor section 32. The second portion 68 of the air 62first flows through the LP compressor 40 in which the rotor blades 46therein progressively compress the second portion 68 of the air 62.Next, the second portion 68 of the air 62 flows through the HPcompressor 42 in which the rotor blades 46 therein continueprogressively compressing the second portion 68 of the air 62. Thecompressed second portion 68 of the air 62 is subsequently delivered tothe combustion section 34. In the combustion section 34, the secondportion 68 of the air 62 mixes with fuel and burns to generatehigh-temperature and high-pressure combustion gases 70. Thereafter, thecombustion gases 70 flow through the HP turbine 48 which the HP turbinerotor blades 54 extract a first portion of kinetic and/or thermal energytherefrom. This energy extraction rotates the HP shaft 58, therebydriving the HP compressor 42. The combustion gases 70 then flow throughthe LP turbine 50 in which the LP turbine rotor blades 54 extract asecond portion of kinetic and/or thermal energy therefrom. This energyextraction rotates the LP shaft 56, thereby driving the LP compressor 40and the fan 14 via the gearbox 60. The combustion gases 70 then exit theengine 10 through the exhaust section 38.

Additionally, the engine 10 may include one or more heat exchangers 100.In general, the heat exchanger(s) 100 heat and/or cool one or morefluids (e.g., oil, fuel, and/or the like) that support the operation ofthe engine 10. Specifically, in several embodiments, the heatexchanger(s) 100 may be operative association with one or morecomponents of the engine 10, such as the fan 14, the compressor section32, the combustion section 34, and/or the turbine section 36. Forexample, in the illustrated embodiment, the engine 10 includes a heatexchanger 100 in operative association with the gearbox 60. In such anembodiment, the heat exchanger 100 may be configured as a fuel-oil heatexchanger that transfers heat from the oil circulating the gearbox 60 tothe fuel supplied to the combustion section 34. However, in alternativeembodiments, the heat exchanger(s) 100 may be in operative associationwith any other suitable component(s) of the engine 10. Moreover, infurther embodiments, the engine 10 may include any other suitable numberor type of heat exchanger 100.

The configuration of the gas turbine engine 10 described above and shownin FIG. 1 is provided only to place the present subject matter in anexemplary field of use. Thus, the present subject matter may be readilyadaptable to any manner of gas turbine engine configuration, includingother types of aviation-based gas turbine engines, marine-based gasturbine engines, and/or land-based/industrial gas turbine engines.

FIG. 2 is a schematic view of one embodiment of a heat exchanger 100suitable for use with a gas turbine engine. In general, the heatexchanger 100 is configured to transfer heat between a first fluid(indicated by arrows 102) and second fluid (indicated by arrows 104).For example, as mentioned above, in one embodiment, the heat exchanger100 may be configured to transfer heat between oil and fuel. However, inalternative embodiments, the heat exchanger 100 may be configured totransfer heat between any other suitable fluids.

The heat exchanger 100 includes a heat exchanger body 106 definingvarious fluid passages, plena, and openings therein through which thefirst and second fluid 102, 104 flow. In several embodiments, the body106 defines a first inlet plenum 108A, a first outlet plenum 108B, and afirst plurality of fluid passages (indicated by solid lines 110)extending from the first inlet plenum 108A to the first outlet plenum108B. In this respect, the first fluid 102 enters the heat exchanger 100(e.g., via an associated port) and flows into the first inlet plenum108A. Thereafter, the first fluid 102 flows through the first pluralityof fluid passages 110 before flowing into the first outlet plenum 108Band exiting the heat exchanger 100 (e.g., via an associated port).Furthermore, the body 106 defines a second inlet plenum 108C, a secondoutlet plenum 108D, and a second plurality of fluid passages (indicatedby dashed lines 112) extending from the second inlet plenum 108C to thesecond outlet plenum 108D. As such, the second fluid 104 enters the heatexchanger 100 (e.g., via an associated access port) and flows into thesecond inlet plenum 108C. Thereafter, the second fluid 104 flows throughthe second plurality of fluid passages 112 before flowing into thesecond outlet plenum 108D and exiting the heat exchanger 100 (e.g., viaan associated access port). As shown, portions of the first plurality offluid passages 110 are routed through the body 106 in close proximity toportions of the second plurality of fluid passages 112, therebypermitting heat transfer between the first and second fluids.

As shown in FIG. 2, the first and second pluralities of fluid passages110, 112 each include two fluid passages. However, the first and secondpluralities of fluid passages 110, 112 may each include any othersuitable number of fluid passages, such a twenty, fifty, or one hundredfluid passages.

FIG. 3 is partial, cross-sectional view of the heat exchanger 100. Inseveral embodiments, the heat exchanger body 106 defines a plenum 108and an access port 116 in fluid communication with the plenum 108.Specifically, in the embodiment shown in FIG. 3, the access port 116extends from an exterior surface 114 of the body 106 to a first interiorsurface 115 of the body 106. For example, as shown in FIG. 5, in someembodiments, the access port 116 has a non-polygonal shape, such acircle, ellipse, oval, filleted/rounded-off rectangle, and or the like.However, in alternative embodiments, the access port 116 may have anyother suitable shape. Moreover, the the plenum 108 may correspond to anyof the plena 108A, 108B, 108C, 108D shown in FIG. 2. The plenum 108extends inward (i.e., relative to the exterior surface 114 of the body106) from the first interior surface 115 to a second interior surface118 of the heat exchanger body 106. As shown, the second interiorsurface 118 is oriented at least partially at an oblique angle(indicated by arrow 120) relative to the first interior surface 115. Inthis respect, the plenum 108 corresponds three-dimensional cavity orspace positioned inward of the exterior surface 114 of the body 106. Forexample, in one embodiment, the plenum 108 may have a conical shape.Moreover, in the illustrated embodiment, the plenum 108 has a closedconfiguration (i.e., the plenum 108 is defined between two interiorsurface of the heat exchanger body 106). However, in alternativeembodiments, the plenum 108 may have any other suitable shape, such as aspherical shape. Furthermore, the plenum 108 may have an openconfiguration. In such a configuration, the plenum 108 extends from anopening defined by the exterior surface 114 to the interior surface 118,with the interior surface 118 intersecting and being oblique to theexterior surface 114.

Additionally, as mentioned above, the heat exchanger body 106 definesthe first and second pluralities of fluid passages 110, 112. As shown,several fluid passages 110, 112 extend through the interior surface 118and intersect the plenum 108 at a corresponding intersection 122. Inthis respect, the fluid passages 110, 112 are in fluid communicationwith the plenum 108 via the corresponding intersections 122. As such,fluid is able to flow from the plenum 108 into the fluid passages 110,112 or from the fluid passages 110, 112 into the plenum 108. AlthoughFIG. 3 shows four fluid passages 110, 112 intersecting the plenum 108,any suitable number (e.g., twenty, fifty, or more) of fluid passages110, 112 may intersect the plenum 108.

As shown, each fluid passage 110, 112 includes a first portion(indicated by arrows 124), a second portion (indicated by arrows 126),and a curved portion (indicated by arrows 128). In several embodiments,the first portion 124 of each fluid passage 110, 112 is positionedproximal to the plenum 108 such that the first portion 124 extendsthrough the interior surface 118 and intersects the plenum 108 at thecorresponding intersection 122. Furthermore, the first portion 124 ofeach fluid passage 110, 112 defines a line of projection 130 thatextends normal or perpendicular to the interior surface 118 of the heatexchanger body 106. Specifically, the line of projection 130 of thefirst portion 124 of each fluid passage 110, 112 is normal to thesection of the interior surface 118 through which the correspondingfirst portion 124 extends. As will be described below, such anorientation of the first portion 124 of each fluid passage 110, 112reduces the stress concentrations present at the intersections 122. Thesecond portion 126 of each fluid passage 110, 112 is distal to theplenum 108 and defines a line of projection 132 extending normal orperpendicular to the interior surface 115 or the exterior surface 114 ofthe body 106. Moreover, the curved portion 128 of each fluid passage110, 112 extends from and fluidly couples the corresponding firstportion 124 to the corresponding portion 126. Thus, each curved portion128 provides a transition between the corresponding first and secondportions 124, which have differing orientations. Additionally, in someembodiments, the first, second, and curved portions of the fluidpassages 110, 112 have the same diameter and cross-sectional shape.

In the illustrated embodiment, the lines of projections 130, 132correspond to the centerlines of the first and second portions 124, 126of the fluid passages 110, 112. However, in alternative embodiments, thelines of projections 130, 132 may correspond to any other suitable linesdefined by the first and second portions 124, 126 of the fluid passages110, 112.

Referring now to FIG. 4, the heat exchanger body 106 may define one ormore stress-reducing features 134. More specifically, as describedabove, the first portion 124 of one of the fluid passages 110, 112extends through the interior surface 118 and intersects the plenum 108at each intersection 122. In this respect, the heat exchanger body 106may define a stress-reducing feature 134 at each intersection 122. Thestress-reducing features 134, in turn, distribute stress over a largerarea, thereby reducing the stress concentrations present at theintersections 122 during operation of the heat exchanger 100. As will bedescribed below, positioning the first portions 124 of the fluidpassages 110, 112 such that their lines of projection 130 are normal tothe interior surface 118 permits the formation of the stress-reducingfeatures 134 at the intersections 122.

The stress-reducing feature(s) 134 may correspond to any suitablefeature(s) defined by the heat exchanger body 106 located at theintersections 122 that distributes stress over a larger area. Forexample, in the illustrated embodiment, the stress-reducing features 134are configured as fillets. However, in other embodiments, thestress-reducing feature(s) 134 may be configured as other rounded edges,chamfers or other beveled edges, and/or the like.

FIG. 5 is a partial cross-sectional of view of the heat exchanger 100.As mentioned above, the fluid passages 110, 112 intersect the plenum 108at the intersections 122. In several embodiments, the intersections 122are arranged non-uniformly or staggered along the interior surface 118defining the plenum 108. Specifically, in some embodiments, theintersections 122 may be arranged in concentric rings along the interiorsurface 118. For example, in the illustrated embodiment, theintersections 122 corresponding to a first set of the fluid passages110, 112 are arranged in a first ring (indicated by dashed line 136)along the interior surface 118. Moreover, in the illustrated embodiment,the intersections 122 corresponding to a second set of the fluidpassages 110, 112 are arranged in a second ring (indicated by dashedline 138) along the interior surface 118. The second ring 138 may, inturn, enclose and/or be concentric with the first ring 136. However, inalternative embodiments, the intersections 122 may be arranged in anyother suitable manner along the interior surface 118 defining the plenum108.

FIG. 6 is another partial cross-sectional view of the heat exchanger100. As mentioned above, each fluid passage 110, 112 includes a secondportion 126. As show, the second portions 126 of the fluid passages 110,112 are arranged into a plurality of rows 140 and a plurality of columns142. The second portions 126 may be evenly spaced apart from each otherwithin each row 140 and within each column 142. Arranging the secondportions 126 of the fluid passages 110, 112 into rows 140 and columns142 may allow the fluid passages 110 to be routed in close proximity tothe fluid passages 112, thereby permitting heat transfer between thefirst and second fluids. However, in alternative embodiments, the secondportions 126 of the fluid passages 110, 112 may be arranged in any othersuitable manner.

In several embodiments, the heat exchanger 100 may be monolithic orformed as single integral component. As such, the heat exchanger 100 maybe formed using a suitable additive manufacturing method. The term“additive manufacturing” refers to any process resulting in a useful,three-dimensional object and includes a step of sequentially forming theshape of the object one layer at a time. Additive manufacturingprocesses include three-dimensional printing (3DP) processes,laser-net-shape manufacturing, direct metal laser sintering (DMLS),direct metal laser melting (DMLM), plasma transferred arc, freeformfabrication, and the like. A particular type of additive manufacturingprocess uses an energy beam (e.g., an electron beam or electromagneticradiation, such as a laser beam) to sinter or melt a powder material.Additive manufacturing processes typically employ metal powder materialsor wire as a raw material.

Positioning of the first portions 124 of the fluid passages 110, 112such that the lines of projection 130 (e.g., the centerlines) of thefirst portions 124 are normal to the interior surface 118 defining theplenum 108 through which the passages 110, 112 extend reduces the weightof the heat exchanger 100. Specifically, such positioning of the firstportions 124 allows the intersections 122 between the fluid passages110, 112 and the plenum 108 to be non-uniformly arranged or staggeredalong the interior surface 118. The positioning of the first portions124 and the non-uniform positioning of the intersections 122, in turn,reduce the stress concentrations present at the intersections 122 duringoperation of the heat exchanger 100. Furthermore, the non-uniformpositioning allows for the formation of stress-reducing features (e.g.,fillets) at the intersections 122, which further reduce the stressconcentrations present during operation. As such, the heat exchanger 100may be formed from lighter materials than conventional heat exchangers(e.g., aluminum instead of steel), while still maintaining the same sizeenvelope and operating under the same fluid pressures.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

Further aspects of the invention are provided by the subject matter ofthe following clauses:

A heat exchanger for a gas turbine engine, the heat exchangercomprising: a heat exchanger body including a first surface and a secondsurface oriented at least partially at an oblique angle relative to thefirst surface, the heat exchanger body defining a plenum extendingbetween the first and second surfaces, the heat exchanger body furtherdefining a fluid passage extending through the second surface such thatthe fluid passage is in fluid communication with the plenum, wherein thefluid passage includes first and second portions, the first portionintersecting the plenum at an intersection and defining a line ofprojection extending normal to the second surface, the second portiondefining a line of projection extending normal to the first surface, thefluid passage further including a curved portion extending from thefirst portion to the second portion.

The heat exchanger of one or more of these clauses, wherein the heatexchanger body defines a stress-reducing feature at the intersection ofthe first portion of the fluid passage and the plenum.

The heat exchanger of one or more of these clauses, wherein the heatexchanger body further defines a plurality of the fluid passagesextending through the second surface such that the plurality of fluidpassages is in fluid communication with the plenum, each fluid passageincludes the first and second portions, each first portion intersectingthe plenum at a corresponding intersection and defining a line ofprojection extending normal to the second surface, each second portiondefining a line of projection extending normal to the first surface,each fluid passage further including a curved portion extending from thecorresponding first portion to the corresponding second portion.

The heat exchanger of one or more of these clauses, wherein theintersections of the first portions of the plurality of the fluidpassages and the plenum are non-uniformly arranged along the interiorsurface.

The heat exchanger of one or more of these clauses, wherein theintersections corresponding to a first set of the plurality of fluidpassages are arranged in a first ring along the interior surface and theintersections corresponding to a second set of the plurality of fluidpassages are arranged in a second ring along the interior surface, thesecond ring enclosing the first ring.

The heat exchanger of one or more of these clauses, wherein the secondportions of the plurality of fluid passages are uniformly spaced apartwithin the heat exchanger body.

The heat exchanger of one or more of these clauses, wherein theplurality of fluid passages corresponds to a first plurality of passagesthrough which a first fluid is configured to flow, the heat exchangerbody further defining a second plurality of fluid passages through whicha second fluid is configured to flow, the second plurality of fluidpassages positioned relative to the first plurality of fluid passagessuch that the second fluid is in thermal communication with the firstfluid.

The heat exchanger of one or more of these clauses, wherein the secondportions of the first plurality of fluid passages are arranged in aplurality of rows and a plurality of columns.

The heat exchanger of one or more of these clauses, wherein the firstportion, the second portion, and the curved portion of the fluid passagehave a same diameter and a same cross-sectional shape.

The heat exchanger of one or more of these clauses, wherein the heatexchanger body is monolithic.

The heat exchanger of one or more of these clauses, wherein the plenumis spherical or conical.

A gas turbine engine, comprising: a compressor, a combustor, a turbine,and a heat exchanger in operative association with at least one of thecompressor, the combustor, or the turbine, the heat exchangercomprising: a heat exchanger body including a first surface and a secondsurface oriented at least partially at an oblique angle relative to thefirst surface, the heat exchanger body defining a plenum extendingbetween the first and second surfaces, the heat exchanger body furtherdefining a fluid passage extending through the second surface such thatthe fluid passage is in fluid communication with the plenum, wherein thefluid passage includes first and second portions, the first portionintersecting the plenum at an intersection and defining a line ofprojection extending normal to the second surface, the second portiondefining a line of projection extending normal to the first surface,each fluid passage further including a curved portion extending from thefirst portion to the second portion.

The gas turbine engine of one or more of these clauses, wherein the heatexchanger body defines a stress-reducing feature at the intersection ofthe first portion of the fluid passage and the plenum.

The gas turbine engine of one or more of these clauses, wherein the heatexchanger body further defines a plurality of the fluid passagesextending through the second surface such that the plurality of fluidpassages is in fluid communication with the plenum, each fluid passageincludes the first and second portions, each first portion intersectingthe plenum at a corresponding intersection and defining a line ofprojection extending normal to the second surface, each second portiondefining a line of projection extending normal to the first surface, thefluid passage further including a curved portion extending from thecorresponding first portion to the corresponding second portion.

The gas turbine engine of one or more of these clauses, wherein theintersections of the first portions of the plurality of fluid passagesand the plenum are non-uniformly arranged along the interior surface.

The gas turbine engine of one or more of these clauses, wherein theintersections corresponding to a first set of the plurality of fluidpassages are arranged in a first ring along the interior surface and theintersections corresponding to a second set of the plurality of fluidpassages are arranged in a second ring along the interior surface, thesecond ring enclosing the first ring.

The gas turbine engine of one or more of these clauses, wherein thesecond portions of the plurality of fluid passages are uniformly spacedapart within the heat exchanger body.

The gas turbine engine of one or more of these clauses, wherein theplurality of fluid passages corresponds to a first plurality of passagesthrough which a first fluid is configured to flow, the heat exchangerbody further defining a second plurality of fluid passages through whicha second fluid is configured to flow, the second plurality of fluidpassages positioned relative to the first plurality of fluid passagessuch that the second fluid is in thermal communication with the firstfluid.

The gas turbine engine of one or more of these clauses, wherein thesecond portions of the first plurality of fluid passages are arranged ina plurality of rows and a plurality of columns.

The gas turbine engine of one or more of these clauses, wherein thefirst portion, the second portion, and the curved portion of the fluidpassage have a same diameter and a same cross-sectional shape.

What is claimed is:
 1. A heat exchanger for a gas turbine engine, theheat exchanger comprising: a heat exchanger body including a firstsurface and a second surface oriented at least partially at an obliqueangle relative to the first surface, the heat exchanger body defining aplenum extending between the first and second surfaces, the heatexchanger body further defining a fluid passage extending through thesecond surface such that the fluid passage is in fluid communicationwith the plenum, wherein the fluid passage includes first and secondportions, the first portion intersecting the plenum at an intersectionand defining a line of projection extending normal to the secondsurface, the second portion defining a line of projection extendingnormal to the first surface, the fluid passage further including acurved portion extending from the first portion to the second portion.2. The heat exchanger of claim 1, wherein the heat exchanger bodydefines a stress-reducing feature at the intersection of the firstportion of the fluid passage and the plenum.
 3. The heat exchanger ofclaim 1, wherein the heat exchanger body further defines a plurality ofthe fluid passages extending through the second surface such that theplurality of fluid passages is in fluid communication with the plenum,each fluid passage includes the first and second portions, each firstportion intersecting the plenum at a corresponding intersection anddefining a line of projection extending normal to the second surface,each second portion defining a line of projection extending normal tothe first surface, each fluid passage further including a curved portionextending from the corresponding first portion to the correspondingsecond portion.
 4. The heat exchanger of claim 3, wherein theintersections of the first portions of the plurality of the fluidpassages and the plenum are non-uniformly arranged along the interiorsurface.
 5. The heat exchanger of claim 3, wherein the intersectionscorresponding to a first set of the plurality of fluid passages arearranged in a first ring along the interior surface and theintersections corresponding to a second set of the plurality of fluidpassages are arranged in a second ring along the interior surface, thesecond ring enclosing the first ring.
 6. The heat exchanger of claim 3,wherein the second portions of the plurality of fluid passages areuniformly spaced apart within the heat exchanger body.
 7. The heatexchanger of claim 6, wherein the plurality of fluid passagescorresponds to a first plurality of passages through which a first fluidis configured to flow, the heat exchanger body further defining a secondplurality of fluid passages through which a second fluid is configuredto flow, the second plurality of fluid passages positioned relative tothe first plurality of fluid passages such that the second fluid is inthermal communication with the first fluid.
 8. The heat exchanger ofclaim 6, wherein the second portions of the first plurality of fluidpassages are arranged in a plurality of rows and a plurality of columns.9. The heat exchanger of claim 1, wherein the first portion, the secondportion, and the curved portion of the fluid passage have a samediameter and a same cross-sectional shape.
 10. The heat exchanger ofclaim 1, wherein the heat exchanger body is monolithic.
 11. The heatexchanger of claim 1, wherein the plenum is spherical or conical.
 12. Agas turbine engine, comprising: a compressor; a combustor; a turbine; aheat exchanger in operative association with at least one of thecompressor, the combustor, or the turbine, the heat exchangercomprising: a heat exchanger body including a first surface and a secondsurface oriented at least partially at an oblique angle relative to thefirst surface, the heat exchanger body defining a plenum extendingbetween the first and second surfaces, the heat exchanger body furtherdefining a fluid passage extending through the second surface such thatthe fluid passage is in fluid communication with the plenum, wherein thefluid passage includes first and second portions, the first portionintersecting the plenum at an intersection and defining a line ofprojection extending normal to the second surface, the second portiondefining a line of projection extending normal to the first surface,each fluid passage further including a curved portion extending from thefirst portion to the second portion.
 13. The gas turbine engine of claim12, wherein the heat exchanger body defines a stress-reducing feature atthe intersection of the first portion of the fluid passage and theplenum.
 14. The gas turbine engine of claim 12, wherein the heatexchanger body further defines a plurality of the fluid passagesextending through the second surface such that the plurality of fluidpassages is in fluid communication with the plenum, each fluid passageincludes the first and second portions, each first portion intersectingthe plenum at a corresponding intersection and defining a line ofprojection extending normal to the second surface, each second portiondefining a line of projection extending normal to the first surface, thefluid passage further including a curved portion extending from thecorresponding first portion to the corresponding second portion.
 15. Thegas turbine engine of claim 14, wherein the intersections of the firstportions of the plurality of fluid passages and the plenum arenon-uniformly arranged along the interior surface.
 16. The gas turbineengine of claim 14, wherein the intersections corresponding to a firstset of the plurality of fluid passages are arranged in a first ringalong the interior surface and the intersections corresponding to asecond set of the plurality of fluid passages are arranged in a secondring along the interior surface, the second ring enclosing the firstring.
 17. The gas turbine engine of claim 14, wherein the secondportions of the plurality of fluid passages are uniformly spaced apartwithin the heat exchanger body.
 18. The gas turbine engine of claim 17,wherein the plurality of fluid passages corresponds to a first pluralityof passages through which a first fluid is configured to flow, the heatexchanger body further defining a second plurality of fluid passagesthrough which a second fluid is configured to flow, the second pluralityof fluid passages positioned relative to the first plurality of fluidpassages such that the second fluid is in thermal communication with thefirst fluid.
 19. The gas turbine engine of claim 17, wherein the secondportions of the first plurality of fluid passages are arranged in aplurality of rows and a plurality of columns.
 20. The gas turbine engineof claim 12, wherein the first portion, the second portion, and thecurved portion of the fluid passage have a same diameter and a samecross-sectional shape.